I'd imagine it's a harder road coming from endurance to back to strength....than from strength back to endurance. If I stop squatting and run/bike for 6 months my endurance will be great...but chances are my squat will suck ass and it will take me a while to get back to where I was.....but if I do squats and heavy lifting with no running/biking for 6 months...my endurance may suck at first but it seems quicker to come back. Probably has something to do with fast and slow twitch muscle fiber conversions as I've heard that fast twitch can act like slow easier than slow to act like fast. So if you train to increase fast twitch, then you can still have endurance capacity.